Can't get a good feel for it; can't tell if the white is silicate (~quartz/feldspar )or carbonate, and can't decide if I'm seeing a slightly schistose texture in the dark part; if I had to have a stab, I'd put it down as metasediment (which is a bit of a cop-out, I know).

Without being able to ID the component minerals and the microscopic textures, it will be difficult to get much better.

Bottom:

Looks somewhat cubic; I'd hazard a guess at fluorspar (rather than halite), though the cream colour doesn't rank as 'familiar' in my book. The dark matrix looks like silt, but what it really is may depend on its situation - eg. it could be rock flour if in a fault-vein cavity.

Again, testing really necessary to make a good ID.

You could try a streak test and scratch hardness test - might rule in/out some candidates.

And locality info would be useful. That might constrain the options to metamorphic, for instance.

Sorry, I agree with Mike that it is difficult to identify from the photographs. Please bring them into the Identification and Advisory Service in the Angela Marmont Centre, at The Natural History Museum, London.You can post them in if you wish.